1. Field of the Invention
The present invention pertains to the field of x-ray imaging systems, including among other things, diagnostic x-ray imaging systems.
2. Background
Real-time x-ray imaging is increasingly being utilized by medical procedures as therapeutic technologies advance. For example, many electro-physiologic cardiac procedures, peripheral vascular procedures, PTCA procedures (percutaneous transluminal catheter angioplasty), urological procedures, and orthopedic procedures benefit from the use of real-time x-ray imaging.
A number of real-time x-ray imaging systems are known. These include fluoroscope-based systems where x-rays are projected into an object to be imaged and shadows caused by relatively x-ray opaque matter within the object are detected on the fluoroscope located on the opposite side of the object from the x-ray source.
Reverse-geometry x-ray imaging systems are also known. In such systems, an x-ray tube is employed to generate x-ray radiation. Within the x-ray tube, high-energy charged particles are generated and focused on a small spot on the relatively large target of the tube, inducing x-ray radiation emission from that spot. The charged particles are deflected (electromagnetically or electrostatically) in a raster scan pattern or otherwise over the target. A small x-ray detector is placed at a distance from the target of the x-ray tube. The detector typically converts x-rays that strike it into an electrical signal in proportion to the detected x-ray intensity.
In known embodiments of reverse geometry diagnostic x-ray imaging system the x-ray source is located above the patient. When these x-ray imaging systems are activated radiation is projected from the x-ray scanning tube, in a generally downward direction. As such, the radiation scatter off of the patient and the x-ray table supporting the patient is generally in an upward direction. Since the scattered radiation is directed predominantly in an upward direction, the attending staff often absorbs the radiation in the most sensitive portions of the body, namely the head and neck. Furthermore, since patients usually lie face up on the x-ray table, when a woman is imaged, her breast tissue, which is more sensitive than other tissue types, is subjected to the direct radiation from the x-ray source.
Thus, there is a need for an x-ray imaging system that minimize x-ray absorption risks to the patient and the attendant staff.